Talk:Before Present

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What is special about 1950?? Georgia guy 22:34, 14 Apr 2005 (UTC)

I'm looking into this for an answer. --Viriditas | Talk 06:25, 18 May 2005 (UTC)
Found it. Adding... --Jemiller226 18:10, 21 May 2005 (UTC)

The "Before Present or Before Physics" section is really sloppy and incoherent. -- Ted

Yes, and its content was apparently also incorrect. Here's another reputable reference besides the one i already quoted in the article:
"B.P. originally did mean "before present" but eventually was changed to mean "before physics" after A.D. 1950 was standardized as the fixed point from which age determinations are (and I hope always will be!) calculated."
--Espoo 19:52, 24 March 2006 (UTC)

explanation of revert[edit]

Jclerman, it is not OK to comment in the article itself on changes in the article. If you feel that AD should be used instead of CE, you should explain that here on the talk page.

Wikipedia is an international encyclopedia and has to take into consideration that many people consider use of Christian terminology in dates inconsiderate and rude. Although Common_Era lists about as many arguments for as against use of CE/BCE instead of the provincial, egocentric, and inconsiderate use of AD/BC, the fact remains that attempts to keep the Christian terminology are doomed to failure. In all truly international contexts where participants are equal and come from different cultures and religions, use of CE/BCE has been the norm for a long time. The following quotes should be enough to make you realise that you're fighting a losing battle and doing nothing but provoking anti-European and anti-US and anti-Christian sentiments:

from Common_Era: More visible uses of common era notation have recently surfaced at major museums in the English-speaking world: The Smithsonian Institution also prefers Common Era usage, though individual museums are not required to use it.[2] As well, many style guides now prefer or mandate its usage. [3][4][5][6][7] Some style guides for Christian churches even mandate its use; for example, that of the Episcopal Diocese of Maryland.(pdf) The usage of the BCE/CE notation is growing in textbooks. It is used by the College Board in its history tests, as well as by the National Geographic Society and the United States Naval Observatory. [8]

from : We use the terms CE and BCE throughout this web site because they are less hurtful to non-Christians. We feel that this outweighs any of the objections to their use of which we are aware. We want to communicate ideas while being civil and considerate to people of all religious traditions. This is compatible with the purpose of this web site, which is to promote religious tolerance. We want to reduce discrimination, oppression and unnecessary pain caused to people on the basis of their religion. Some people call this being "politically correct" because it is sensitive to the feelings of others. That is their right. But we feel that the use of CE and BCE is the decent and considerate thing to do.

I also question the reasoning behind your changes of the quotes:

1) There is no reason to remove the explanation [U.S. National Bureau of Standards]

2) Splitting the explanation of the meaning into two parts is unnecessary and complicates the issue, and your paraphrase of the second part is so much more complicated that it's incomprehensible to most:

"redefined the meaning of the P in BP from the actual year of the laboratory analysis to Physics" is nonsense compared to the original's clarity: " redefined the meaning of B.P. from 'Before Present' to 'Before Physics' "

In addition, this note was confusing and irrelevant because there were and are no claims to the contrary: "Definitions such as BP can not be changed ad libitum but only by consensus obtained at international commitees."

Finally, you used nine edits to change only three things. This makes it difficult for others to decide which of your edits are OK and which not. Please use the "Show preview" button to check your edits before pressing "Save page".

--Espoo 04:34, 31 March 2006 (UTC)

I couldn't agree more; I was distressed to find AD used without comment in a Wikipedia entry. There is no rationale or excuse for using a term that has the name of one religion's principal deity in a non-religious context, especially when the alternative is the standard in academia.. and basically everywhere except Christians writing for Christians. Sebum-n-soda (talk) 01:20, 12 January 2012 (UTC)


look at Maglemosian_culture and many other articles and you will see that BP is rarely used and AD or BC is much more commonly used. If BP or BP cal was commonly used there would be a bot that would convert all the AD and BC and CE etc. references to BP. Als this article here nowhere says how the year 1965 AD is represented. Is is AP? BP+15 or some other way of expressing it? If these aspects are not dealt with then BP is a limited specialist use even if one big museum or some scientists use it in their terminology they are a minority. — Preceding unsigned comment added by (talkcontribs)

This is a complete misunderstanding of the use of BP. We go by what our sources say, and many of those that actually use radiocarbon dating provide dates expressed in BP. We can't change that and shouldn't. Scientists using BP aren't in a minority of scientists using radiocarbon dating, which never converts exactly to ordinary calendar dating. The article you site has no dates for radiocarbon dated material in it, so is irrelevant. Dougweller (talk) 18:06, 6 April 2015 (UTC)


I just added UTC to the list of dating systems. Wikipedia uses UTC as its standard. While this is not clear it does mean either the Julian or the Gregorian must be followed and if they (which is likely as they were started by Catholic Popes) use AD or BC then these are correct teminology. It is not clear though which should be used prior to these dates I guess the Julian Day article shows the difficulty and I would guess the English wikipedia goes for the Gregorian, but using Julian dates prior to its introduction according to what each country did, so Russian dates will not match with English dates for example. (talk) 18:53, 23 August 2015 (UTC)Mpetz178.190.193.212 (talk) 18:53, 23 August 2015 (UTC)

And I'm just about to take it out again, if not already done. UTC is not a dating system, it is a time system. [It gives the time of day on planet Earth as at the prime meridian, 0 degrees. To find the equivalent local time of the Wikipedia time-stamp at your location, see your local time-zone conversion factor, which is expressed as UTC±n. See UTC.


Currently BP in WP means British Petroleum. This means that at least some articles link to British Petroleum (as in ' 26,000 BP ' when 'before present' is meant. It also means editors have to code the cumbersome ' 26,000 BP ' to correctly link to this article. Any support for the idea of trying to get article BP to be a redirect to 'Before Present' and making a 'BP (oil)' article to handle the oil company. Hmains 19:43, 30 December 2006 (UTC)

Hello, I'm going through and fixing bad links like the example you gave, and I ran across your comment. I'm afraid I must disagree. The three main uses of "BP" or "bp" are those meaning "Before Present", "Base Pair(s)" (biology), and "British Petroleum" (the company). There are approximately 170 links within Wikipedia that want the "Before Present" meaning, about 90 for "Base Pair(s)", but over 600 for British Petroleum. Judging by that, "British Petroleum" is by far the most common meaning. Yes, it's annoying; I don't like it, either, but it's reality. --Tugbug 21:02, 15 May 2007 (UTC)

This article is too limited[edit]

bp is not just used for radiocarbon dating, i.e. for times less than 60 ka, but very generally in geology, palaeology and others. For palaeolithic times, i.e. those where many other physical measures besides radiocarbon are in common use, bp is the generally accepted way to state time and radiocarbon datings tend to be given as calibrated years BP to fall in line. Axel Berger 00:42, 26 February 2007 (UTC)

I've Never Run Into the Phrase "Before Physics"[edit]

We used to joke about events dated "After Present" (historical dates, not radiocarbon ones). Jacob Haller 21:38, 17 March 2007 (UTC)

but you just did! Jclerman 22:35, 17 March 2007 (UTC)
OMG, AP -- that's hilarious! I'm going to use it and everyone will think I'm SO clever! BTW, I know the guy who invented the "before physics" meaning (Hans Sues, the brother-in-law of my friend). I'll ask him if he intended it to be used seriously, as it sounds to me like a joke (as physics existed before 1950). if so, I'll remove the section. —Preceding unsigned comment added by TechnoFaye (talkcontribs) 15:50, 7 April 2008 (UTC)
No attribution to boot. I suggest surgically removing it. Kortoso (talk) 20:28, 7 July 2016 (UTC)

Radiocarbon nonsense[edit]

I am a geophysicist. To say that this is only about radiocarbon or only about estimated ages is radically wrong. For example, BP is routinely used for ice cores, which are never dated with radiocarbon (i.e. [1] [2] [3]). BP means years before 1950 whether or not they are "estimated radiocarbon years" or "calendar years". Dragons flight 17:51, 16 May 2007 (UTC)

Also note Axel Berger's comment above. Dragons flight 17:53, 16 May 2007 (UTC)
Those BP years used for geologic time don't need to be anchored in AD 1950 as required for the BP radiocarbon years. The ice cores are anchored in AD 1950 because they are isotopically studied by geochemists in environmental isotopes labs (C14, and stable C, O, etc) and because the yrs are counted with an accuracy of 1 yr.Jclerman 18:53, 16 May 2007 (UTC)u
They are expressed in years BP because counting backward is a useful convention for measuring the gelogic time, same as Ma, Ga, etc. for longer intervals. There is nothing that requires years BP to reference radiocarbon and normal usage in ice core work would be for "BP" to mean calendar years BP. Dragons flight 20:08, 16 May 2007 (UTC)
"BP" is NOT "routinely used for ice cores". E.g., Danish researchers have long ago switched to the much more intelligent "b2k" (before the year 2000), since the misuse of a common word like "present" for 1950 becomes the more ridiculous, the more we part from that year. Moreover, it can too easily be confused with the correct, conventional use of "BP", and thus repeatedly leads to tremendous errors in many papers. HJJHolm (talk) 12:39, 28 August 2009 (UTC)
It's also used for radiometric dating. Kortoso (talk) 20:44, 7 July 2016 (UTC)

Comments on Rewrite[edit]

(This refers to the 00:08, 18 May 2007 edit by Tugbug.)

It's amazing that such a simple, ordinarily non-controversial topic should be the scene of so many reverts lately. Sadly, this is resulting in a messy article. In my experience, the best thing to do in such situations is a rewrite. I have done one. See what you think.

My guiding principles:

  • BP years are used for all kinds of dating (ice cores have been mentioned, etc.), not just radiocarbon.
  • However, BP years were standardized by people doing radiocarbon dating, with their particular application in mind. Thus, radiocarbon dating should be considered the primary and motivating application of the BP scale.
  • BP always means years before 1950 when the uncertainty in dates is small, and years before some date relatively close to the present when the uncertainty is large. Thus, years before 1950 is always an acceptable definition.
    If anyone knows of any exceptions to this, speak up.
  • The article does not need a separate section for every little topic that pops up.
    I've taken it from 6 sections to 3.
  • Everything in the article should have particular relevance to the BP scale.
    Thus, I've removed the mention of cal BC, cal AD.
  • References should be given in a form that allows them to be looked up.
    Thus, for now, I have removed references that were only a name and a year. I found and included a complete citation for the Arnold-Libby paper. I removed the Mook-van der Plicht reference, since I could not get at it due to a subscription requirement; I also can not tell what it was included for. References certainly can be replaced if they can be given in more detail and/or made accessible.

--Tugbug 00:09, 18 May 2007 (UTC)

References need improvement[edit]

Reference 1 is to a website that uses the term but doe not establish a solid reference, which then refers to a paper which is in itself also uses BC/SD and is not a secondary reference to the origin or establishment of the term. I have added Template:Fact tags. Fireproeng (talk) 22:47, 17 February 2008 (UTC)

Gee Whiz[edit]

I didn't know we were 58 years in the future. (talk) 19:18, 29 April 2008 (UTC)

The whole concept is ridiculous. The first rule of communication is to be understandable. Everyone knows what year you mean when you say "1000 B.C." If you say "BP" and really mean "1950" as "present" then you've made it harder to communicate. "BP" as a concept fails basic communication tests. -- (talk) 19:55, 26 August 2008 (UTC)
That depends who you're talking to. If its someone who understands radiocarbon dating, it makes perfect sense. Until 1950 the proportion of C14:C12 in the air was relatively constant. Then atmospheric nuclear weapons testing messed it up. So we take a carbon sample, and measure its 14/12 ratio. Log base 2. Divide by the 1950 atmospheric equivalent to get the number of half lives. Multiply by the half-life of C14. Get the number of years BP (uncalibrated). It's so silly, it won a Nobel prize. LeadSongDog (talk) 00:40, 27 August 2008 (UTC)

I agree. This pretentious pseudointellectual bs has to stop. Don't let these twits take over Wikipedia. Who cares if its convienent for radiocarbon dating, convert it to AD/BC and stop being idiots. You're all worse than Americans with thier imperial system. (talk) 13:39, 27 September 2009 (UTC)


  1. REDIRECT Before Present —Preceding unsigned comment added by (talk) 00:17, 27 May 2008 (UTC)

BP "years" are not the same as caledar "years"[edit]

I think it should be pointed out that BP "years" do not correlate nicely to calendar "years". For example, you can not simply subtract 10,000 from 1950 to figure out what callendar date equates to the date 10,000 BP. As time passes the BP "year" covers a longer period of time than one calendar "year". Its something to do with how carbon isotopes decay. Blueboar (talk) 15:04, 1 June 2009 (UTC)

This only applies to "uncalibrated C-14 years". Most other fields do apply a 1-1 correspondence. It's not really an issue with BP so much as it is an issue with how carbon dating is reported. Dragons flight (talk) 15:11, 1 June 2009 (UTC)
This is not my area of expertise, so I will bow to your knowledge... but I was under the impresson that BP was not always calibrated (and as the date gets older can not really be calibrated with any certainty.) It isn't a one to one ratio. In other words: 10,000 BP does not equal 8050 BC (1950 - 10,000). Am I misinformed? Blueboar (talk) 23:22, 2 June 2009 (UTC)
A date reported as "10000 C-14 years BP" behaves as you suggest, but the counterpoint is "10000 calendar years BP" (cal. BP) which is one-to-one. When BP is used away from C-14 it is basically always calendar years. So the uncertainty you describe is a property of carbon dating, not a property of using BP notation. In technical literature a carbon dating number should always be labeled calibrated or uncalibrated in addition to saying BP, etc. Dragons flight (talk) 00:27, 3 June 2009 (UTC)
There are a great many basis systems in use in stratigraphic analysis, from tree rings to layers in ice cores to layers in seabottom sediments. Many atmospheric factors vary year to year on a global scale leaving patterns that can be seen, repeated, in cores from widely varying sites, so that the corresponding layer in different cores can be identified as the same year. Counting layers in the cores gives exact integer year counts. Occasional fortuitous carbonaceous inclusions in the layers provide C12/C14 ratios for those exactly known years. These become calibration reference data points for converting radiocarbon dating to calibrated dating. Use of these tables allows for corrections for annual perturbations in the atmospheric C12/C14 ratios caused by major volcanic activity (increases) versus sunspots or forest fires in drought years (decreases). LeadSongDog come howl 04:33, 3 June 2009 (UTC)
While you are broadly correct, I don't think there has ever been a countable ice core of any significant age with a large enough carbon content to be reliably measurable using C-14. As discussed at radiocarbon, calibration curves generally use dendrochronology, cave deposits, and corals. The last two are generally cross-dated with U-Th or similar techniques. Dragons flight (talk) 04:49, 3 June 2009 (UTC)
Right, ice cores are of little use in C14 dating per se, but they are useful for relating overall atmospheric CO2, N2, O2 partial pressures. For C14 dating this has to be cross referred to other data as you say.LeadSongDog come howl 07:22, 3 June 2009 (UTC)
I think I understand better now... but all this needs to be better explained in the article. Thanks. Blueboar (talk) 14:45, 3 June 2009 (UTC)
This is all correct, and therefore the misuse of "BP" outside the conventional radiocarbon dating should not be tolerated. Moreover, the chapters on radiocarbon dating here intersect the proper wikipedia articles and must be removed.HJJHolm (talk) 12:42, 28 August 2009 (UTC)
Could you please clarify this statement, HJJHolm? Links to the "proper" wp articles might help.LeadSongDog come howl 13:06, 28 August 2009 (UTC)
It is not our job to decide what should and should not be tolerated. People working in paleoclimate, uranium-thorium and other methods frequently use BP to mean calendar years. Wikipedia needs to document things as they are not as we wish they would be. Dragons flight (talk) 18:35, 28 August 2009 (UTC)
What is "calendar year" supposed to mean anyway? What's the other kind of year? Fiscal year? It make me crazy. Kortoso (talk) 20:48, 7 July 2016 (UTC)

"BP" and "bp"[edit]

Shouldn't the convention of using uppercase and lowercase letters (for calibrated and uncalibrated dates) be mentioned as well? — (talk) 16:40, 27 June 2010 (UTC)

Do we have wp:Reliable sources showing this convention is still practiced? LeadSongDog come howl! 01:06, 28 June 2010 (UTC)

Recommendations of the style guide of the Society for American Archaeology[edit]

I suggest to regard the style guide of the Society for American Archaeology here: When reporting radiocarbon dates and ages, the following information should be included: In the first citation, the uncalibrated radiocarbon age must be given. The uncalibrated radiocarbon age must be

  • Based on the 5,568-year 14C (radiocarbon ages based on the 5,730-year half-life must be divided by 1.03),
  • Expressed as years BP (i.e., Before Present; do not convert to radiocarbon years AD/BC),
  • Followed by the 1-sigma (σ) standard error, as provided by the laboratory,
  • Accompanied by the sample identification number given by the laboratory (use conventions for laboratory code abbreviations as provided in the journal Radiocarbon)
  • Accompanied by the type of material that was dated (e.g., wood charcoal, corn cob),
  • And defined as to whether the date was corrected for isotropic fractionation (a 13C value indicates correction has been made; best way to indicate this is to include the 13C value if available).

An example of an uncalibrated radiocarbon age is 480 ± 70 BP (ISGS 5965; plant [Pragmites sp./Equisetum sp.]; δ13C, −25.1). When calibrated dates are included, they must be identified as such by using the conventions "cal AD" or "cal BC," and the calibration used must be identified. Indicate whether the calibration was made for 1σ or 2σ (the latter is preferred), and present the calibrated age as a range of calendar age. If there is more than one possible range of age, include any probabilities provided by the calibration program. (For the date 3680 ± 60, the two possible calibrated age ranges are 2279–2232 cal BC [p = .05] and 2209–1905 cal BC [p = .95].) An example of a calibrated radiocarbon age is ca. cal AD 1480–1532 (calibrated with CALIB 5.0 at 2σ). — Preceding unsigned comment added by HJJHolm (talkcontribs) 10:19, 21 March 2012 (UTC)

That sounds good. Is this the link?[1] Kortoso (talk) 20:51, 7 July 2016 (UTC)

b2k - relevant to this article?[edit]

Whilst I accept that 'b2k' (before 2000) can be cited, I don't understand why it belongs in this article. Indeed I think its inclusion is confusing because 'present' in BP doesn't mean 'today', it means 'before the atomic isotope record was disrupted by nuclear weapons [testing]'. So adding stuff about Y2K undermines that point. In my view, 'b2k' needs its own article and no more than a mention in the 'see also' in this one. --John Maynard Friedman (talk) 16:30, 28 October 2014 (UTC)

AUC - Ab Urbe Condita[edit]

I added AUC in See Also. I think it is a good addition for the article. Reinsalkas (talk) 14:27, 14 November 2014 (UTC)


Apparently there is a different convention using YBP or ybp, which is frequently found on Wikipedia (search), but not mentioned in the article. While YBP redirects somewhere else, ybp does redirect here, so it should be mentioned. See also wikt:YBP and wikt:ybp. I think the "Y" is redundant, since BP alone will already be understood to mean (radiocarbon) years per convention, but clearly this abbreviation is in use. --Florian Blaschke (talk) 06:02, 2 June 2015 (UTC)

I've changed YBP, so that now both YBP and ybp redirects to this article.--Cyfal (talk) 17:48, 7 February 2016 (UTC)

Radiocarbon calibration[edit]

I have just deleted a sentence at the end of the "Radiocarbon calibration" section because it does not make sense. It read "Many scholarly/scientific journals demand to add the calibrating laboratory code with year, because of differences and progress in quality." (To which someone had rightly added the superscript "[clarification needed]"!). I suspect it was a non-native English writer attempting to say something like "Many scholarly/scientific journals require that the year be accompanied by the code of the calibrating laboratory, because of differences between the methods used by different laboratories and advances in quality." If someone wishes to revert that sentence, I hope it can be done in clear English, perhaps along the lines of my suggestion.UBJ 43X (talk) 14:57, 9 September 2016 (UTC)

"calendar years"[edit]

The article states that " "cal" indicates "calibrated years", or "calendar years" ". I may be wrong but I don't think I've ever seen "cal" used as an abbreviation for "calendar years" in dating. Even if it is sometimes used in this way (?), such would require a new sentence, to avoid confusion. At the moment you end up with the absurd scenario of "cal BP" meaning "calendar years, before present". — Preceding unsigned comment added by (talk) 21:11, 16 February 2017 (UTC)


Why is the subject of the article always referred to with both words capitalized? Is it a proper noun and normally written like that? — Preceding unsigned comment added by LearnerGenius (talkcontribs) 01:12, 10 August 2017 (UTC)